This invention relates a tool for aligning sheaves or the like rotatable about spaced-apart parallel axes of rotation.
Many types of mechanical systems involve the use of two or more sheaves, pulleys or the like which are rotatable about spaced-apart parallel axes of rotation. In some such systems, it is often periodically necessary to align the sheaves or pulleys. Alignment between any two sheaves is generally assured in three different ways: (1) by assuring the axes of rotation of the two sheaves are spaced apart within given tolerances; (2) by assuring that planes perpendicular to the axis of rotation of each sheave are parallel, this being equivalent to the axes of rotation of the two sheaves being parallel; and (3) by assuring alignment along the axes of rotation.
An example of such a mechanical system is the drive system of a snowmobile consisting in part of the drive clutch, drive belt, and driven pulley. The drive system used in the Arctic Cat.TM. snowmobile, for example, uses a torque sensing, sheave-type, variable ratio drive clutch and driven pulley. The combination of the drive clutch, drive belt and driven pulley acts an automatic transmission. The drive ratio between the engine and the track of the snowmobile is governed by the radial position of the drive belt on the drive clutch and driven pulley respectively. The drive belt is a cogged v-belt and the drive clutch and driven pulley include v-shaped grooves for the drive belt similar to common v-belt sheaves. However, in the case of the snowmobile drive system, the sheaves each comprise two halves, one half to each side of the drive belt. As the two sides of a sheave move closer together, the drive belt moves radially outwards on the sheave and, as the halves of the sheaves move farther apart, the drive belt moves radially towards the axis of rotation of the sheave. When the snowmobile is starting off and during heavy loading, the halves of the drive clutch are spaced apart the maximum distance and the halves of the driven pulley are closest together. During high speed cruising and light loading, the halves of the drive clutch are closest together and the halves of the driven pulley are furthest apart. In this way the ratio of the drive clutch and driven pulley is variable between, for example, 3.79:1 and 1:1 for the two cases just described.
In the past, proper alignment of the drive clutch and driven pulley has been considered a frustrating and time consuming operation. The recommended approach involves the use of a straight clutch alignment bar with parallel faces. With the drive belt removed, one end of the clutch alignment bar was inserted between parallel faces of the two halves of the driven pulley. The other end of the bar was placed on a small block on the shaft of the drive clutch. Measurements were then made from a face of the clutch alignment bar to certain portions of the drive clutch. In this way, by making certain adjustments until these measurements were within given tolerances, both "parallelism" and "offset", equivalent to the second and third forms of alignment mentioned above, were assured. Parallelism was assured, however, only in the direction joining the axes of rotation of the drive clutch and driven pulley, and not in the perpendicular direction.
United States Patents which may be considered relevant to this application include U.S. Pat. No. 3,359,642 to Jessen; No. 2,821,788 to Wendt; No. 2,059,407 to Spase; No. 1,554,610 to Webster; No. 1,984,231 to Parker; No. 2,067,442 to Frisz; No. 2,711,935 to Miles; No. 978,177 to Locke and No. 1,410,432 to Wallin. However, none of these patents reveals a clutch adjusting tool resembling that of the present invention.